This invention relates to polyethers containing perfluoroalkyl groups. More particularly, this invention concerns 1,2-polyether glycols containing perfluoroalkyl groups and the synthesis of these 1,2-polyether glycols containing perfluoroalkyl groups, their use as surfactants in the paint and lacquer industry and as polyol components in the preparation of polyurethanes from polyols and polyisocyanates.
The invention further relates to polyethers having perfluoroalkyl groups and a terminal oxiran group as an intermediate.
Aliphatic organic fluorine compounds have found much interest in industry. The compounds are used as chemical lasers, functional liquids, hydrophobizing and lyophobizing agents, antistatic agents, surfactants, for the production of extinguishing foams and for many other purposes, in which interfacial phenomena are important. The structure of suitable compounds, their synthesis and properties are summarized in "Tenside", 13 (1976), 1-5 and in "Chemiker Zeitung" 99 (1975), 477-485 and 100 (1976) 3-14.
The state of the art also includes German Patent 3.541 515. This patent concerns polyethers containing perfluoroalkyl groups which have the general formula ##STR2## wherein R.sup.1 is an alkylene group having at most 3 carbon atoms which connects the two hydroxyl groups,
R.sup.2 is hydrogen or a methyl, ethyl or phenyl group, PA0 R.sup.3 is hydrogen or a methyl group, PA0 n is a number from 2 to 14, the value of which may vary within each molecule PA0 m is a number from 2 to 20, PA0 x is a number from 2 to 50. PA0 R.sup.4 is hydrogen or a methyl, ethyl or phenyl group, in a known manner in a solvent and in the presence of a free radical forming agent with a perfluoroalkyl iodide of the general formula C.sub.m F.sub.2m+1 I, reacting the intermediate obtained in a known manner with alkali or alkaline earth hydroxide in at least equimolar amounts with respect to the iodine groups, freeing the product from the alkali or alkaline earth iodide formed and removing the solvent. PA0 n has an average value of 4 to 12, PA0 a has an average value of 0 to 4, PA0 m has an average value of 2 to 18, PA0 x has an average value of 2 to 50 and PA0 y has an average value of 0 to 3.
The polyethers of aforementioned German Patent 3,541,515, which contain perfluoroalkyl groups, can be synthesized by reacting compounds of the general formula ##STR3## wherein R.sup.1, R.sup.3, n and x have the meaning given,
The aforementioned compounds are effective defoamers for aqueous, optionally pigmented, polymer dispersions. They prevent the formation of macrofoam and cause macrofoam which has already formed to collapse. At the same time, any microfoam which leads to so called pinholes in paint films is kept at a low level or suppressed.
However, when these compounds are used for certain applications, particularly when they are added to paint systems Which are exposed to the elements, it turns out that they are susceptible to oxidation because of the olefinic double bonds that are present. Moreover, the compounds have an inherent yellow to yellow-brown color, which presumably is attributable to a content of ionically bound iodine. This inherent color interferes, especially when the polyetherols are to be used as reactive polyol components for the preparation of polyurethanes.